A fuel cell includes a Membrane-Electrode-Assembly (MEA) provided with a catalyst layer for a reaction of hydrogen and oxygen, and separators provided at both sides of the MEA where water is discharged while hydrogen and air are supplied into an interior of the MEA. In the fuel cell, a plurality of manifolds through which hydrogen and air may flow is provided, such that hydrogen or air may be supplied to a plurality of fuel cells when the fuel cells are stacked. In addition, passages are provided for supplying hydrogen or air to react with the MEA while the hydrogen or air flows are provided between the both ends of the separator.
In general, the hydrogen introduced through the manifold disposed at a first end of the separator may be discharged to an exterior through a manifold disposed at a second end of the separator after passing through the passages. Since the introduced hydrogen reacts and the hydrogen discharged to the exterior is still a reactant, a hydrogen circulator is configured to reintroduce the discharged hydrogen into the manifold disposed at the first end of the separator.
In the related art, a hydrogen circulating apparatus configured to supply and recirculate hydrogen is disposed within a fuel cell stack of a vehicle, which includes: a fuel cell stack having an hydrogen inlet and a hydrogen outlet, a hydrogen circulator connected to the hydrogen outlet of the fuel cell stack, a water trap disposed between the hydrogen inlet of the fuel cell stack and the hydrogen circulator, and a hydrogen supply source connected to the hydrogen inlet of the fuel cell stack. In particular, the hydrogen supply source 16 is connected to the hydrogen outlet 14 of the fuel cell stack 10 and the hydrogen circulator 18 is directly connected to the hydrogen inlet 12 of the fuel cell stack 10 by removing the water trap 20.
However, such an apparatus for recirculating hydrogen installed to the exterior of the fuel cell deteriorates the advantageous configuration of a package. Further, condensate may be additionally generated by an external heat loss, which deteriorates stack humidifying operation. In addition, a pressure loss may be generated in pipes. Moreover, since a substantial mixture gas of hydrogen, nitrogen, and vapor is supplied to an inlet of the stack, properties of the gas may change when the gas flows in a stacking direction thereby generating deviation between the cells. In particular, cost for a loop of the external circulation structure which is driven by an ejector, a hydrogen compressor, and the like is high.
In addition, reducing the sizes of the plurality of manifolds to stably supply reactants has been limited, and increasing the sizes of the passages has been limited as well, and thus an energy output density of the fuel cell may have not been improved.
The description provided above as a related art of the present invention is just for helping in understanding the background of the present invention and should not be construed as being included in the related art known by those skilled in the art.